On my last E46 M3 I set the front suspension to full negative camber and reduced the toe in (but kept to a slight negative setting ~5 minutes IIRC) and it did indeed improve the turn in and give more mid corner grip...the downside was a loss of stability to the extent of having to back off slightly when trying to press on in country lanes with a poor road surface.
Once the car is set up with the new suspension and realigned you can tinker with the Toe setting as it can be adjusted independantly without influencing the rest of the set up.

Indeed, I was planning on doing the same after I get new tyres fiiting and geo set-up. What front and rear toe angles are you running Senor?